[英]React Component props won't update
当我发送图像数组时, this.props.images
没有正确更新。 该数组仅显示为空,但结果数组不是。
我已经为该项目链接了我的 repo 并列出了需要引用的文件。
需要查看的文件如下:
如果你想通过贡献来帮助这个项目,那就太好了! :)
也许你应该在组件生命周期中使用 componentWillReceiveProps
请参阅反应文档--> 此处
或者只使用 pureComponents(函数下层类)
pureComponents 默认更新 props
我试过运行你的应用程序,但没有用。 因此,下面的代码假设其他所有内容都已在您的应用程序中设置并正常工作。
不要使用类装饰器@
,而是尝试直接连接到类(另外,我强烈建议清理您的代码,它真的很难阅读)。
几个注意事项:
this.update()
-- update WHAT!?!? 虽然这对您来说很有意义,但对于从未见过您的应用程序的开发人员来说,他们会问同样的问题)image
和images
。 有什么不同? 如果一个是用于索引的数字,另一个是用于图像的数组,那没关系,您仍然可以使用单个reducer(如下所示)。actions
文件夹来处理 Redux 动作和一个用于 Redux 类型的types
文件夹fetch
)Upload Images
表单。 不要将它与您的Images
组件混为一谈。state
。types/index.js (redux 操作类型)
export const UPDATE_IMAGE_INDEX = "UPDATE_IMAGE_INDEX";
export const UPDATE_IMAGES = "UPDATE_IMAGES";
reducers/imagesReducer.js (像这样构建你的switch/case
)
const initialState = {
index: 0,
data: []
}
const imagesReducer = (state=initialState, { type, payload }) => { //es6 destructing -- type=action.type, payload=action.payload
switch (type) {
case 'UPDATE_IMAGE_INDEX':
return { ...state, index: payload } // accessible via state.images.index
case 'UDPATE_IMAGES':
return {...state, data: payload } // accessible via state.images.data
default:
return state
}
};
export default imagesReducer;
动作/图像动作(redux 动作创建者)
import * as types from '../types';
// the following is a Redux thunk action (thunk handles returned async functions -- you have to install it and add it as middleware)
export const fetchImages = (id, type) => dispatch => (
fetch(`/images/${type}/${id}`) // fetch images
.then(res => res.json()) // turn result into JSON
.then(({ result }) => dispatch({ type: types.UPDATE_IMAGES, payload: result })) // send result to `imagesReducer`
.catch(() => console.log('Network error...'));
)
// this updates the image index
export const updateImageIndex = payload => dispatch => (
dispatch({ type: types.UPDATE_IMAGE_INDEX, payload })
)
// this should upload an image, save it, then return all current images
export const uploadImage = (type, id, data) => dispatch => (
fetch(`/images/${type}/${id}`, {
method: 'POST',
body: data
}
)
.then(res => res.json())
.then(({ result }) => dispatch({ type: types.UPDATE_IMAGES, payload: result }))
.catch(() => dispatch({ type: 'UPDATE_ERROR', payload: { message: 'Network error...try again later!'} }));
)
components/Content/Profile/ShowImages.js (显示图像——没有别的;另外,允许你通过按钮一一查看)
import React, { PureComponent } from 'react'
import { connect } from 'react-redux'
import { fetchImages, updateImageIndex } from '../../../actions/imageActions';
class ShowImages extends PureComponent {
componentDidMount = () => {
inputs.lazyload(`/css/images.min.css`).catch(() => console.log('Network error...'));
this.props.fetchImages(this.props.type, this.props.id); // fetches images via redux action creator shown above
}
handlePrevClick = e => {
const { index, images } = this.props;
if (index-1 <== images.length) {
this.props.updateImageIndex(index-1); // reduces redux image index by 1 via redux action creator shown above
}
}
handleNextClick = () => {
const { index, images } = this.props;
if (index+1 <== images.length) {
this.props.updateImageIndex(index+1); // increases redux image index by 1 via redux action creator shown above
}
}
// ideally this should be done BEFORE being sent to the front-end, as is, every time this.props.index is updated, this has resort them -- ruins client-side performance and wastes resources.
sortImages = () => {
return this.props.images.sort((a, b) => {
if (a.isDefault && b.isDefault) return a.src.localeCompare(b.src);
return a.isDefault || b.isDefault;
});
}
render = () => {
const { index, images } = this.props;
const sortedImages = this.sortImages();
const prev = images.length && index > 0 ? '<' : '+';
const next = images.length && index < images.length ? '>' : '+';
return (
<div className='images'>
<button className='prev' onClick={this.handlePrevClick}>
{prev}
</button>
<img src={sortedImages[index]} />
<button className='next' onClick={this.handleNextClick}>
{next}
</button>
</div>
);
}
}
const mapStateToProps = state => ({
images: state.images.data,
index: state.images.index,
user: state.user,
type: store.current.type
})
const mapDispatchToProps = dispatch => ({ fetchImages, updateImageIndex });
export default connect(mapStateToProps, mapDispatchToProps)(ShowImages)
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